1. Field of the Invention
The invention relates to a ball bearing, and an inner ring and an outer ring thereof.
2. Description of the Related Art
As an existing ball bearing used for a fuser roller or a heating roller of a copying machine, a ball bearing 101 shown in FIG. 5 is used. The ball bearing 101 is arranged between a shaft end portion 102A of a rotary shaft (roller) 102 and a metal-sheet housing 103, and fitted to the shaft end portion 102A and the metal-sheet housing 103. A snap ring 105 is fitted in an annular groove 104 formed in the shaft end portion 102A. The snap ring 105 restricts the axial position of the ball bearing 101 to prevent the ball bearing 101 from dropping off.
In order to facilitate fitting and removal of the ball bearing 101, the ball bearing 101 and the metal-sheet housing 103 are loosely fitted to each other and the ball bearing 101 and the shaft end portion 102A are also loosely fitted to each other.
Therefore, creep is likely to be generated between an inner ring 106 of the ball bearing 101 and the shaft end portion 102A and between an outer ring 107 of the ball bearing 101 and the metal-sheet housing 103. Accordingly, there is a concern that abnormal noise may be caused due to backlash. In addition, there is a concern that abrasion power may enter the ball bearing 101, resulting in reduced bearing life.
Especially in a ball bearing used for a fuser roller or a heating roller of a copying machine, formation of backlash due to creep and generation of abrasion power become pronounced. This is because a load of several tens of kilograms is applied to the roller in order to fuse ink into paper and feed paper, and, in addition, the load applied to the roller has been increased in recent years due to an increase in the speed of paper feed.
Japanese Patent Application Publication No. 51-86662 (JP-A-51-86662) describes that a bearing 201 is locked to a shaft 203 by a wire 206, a snap ring or a circlip so that relative movement between these members in the axial direction is restricted, as shown in FIG. 6.
With the technology described in JP-A-51-86662, although it is possible to suppress formation of axial backlash between the bearing 201 and the shaft 203 to some extent, it is not possible to prevent generation of creep.
Japanese Patent Application Publication No. 09-144763 (JP-A-09-144763) describes that an inner ring and an outer ring are produced by pressing metal sheets.
According to the technology described in JP-A-09-144763, however, the radial movement of an inner peripheral face of the inner ring is restricted by an end face, an outer side raceway groove and a load backup portion. Therefore, it is not easy to tightly fit the inner ring to a rotary shaft. If the inner ring is forcibly fitted to the rotary shaft, unexpected deformation may occur.